Objective: To evaluate the initial response to EFV-based HAART and the evolution of those changes over time on HAART in HIV infected previously ART-naive patients in South India. Comparison with a matched, untreated group will allow us to differentiate the role of antiretrovirals versus the natural progression of HIV infection on the nutritional status, metabolic, body shape, body composition and bone parameters. These data have not been previously reported from Asia. Specific Aim I: In the treatment group, a)To describe the nutritional, body shape and metabolic responses to the initiation of therapy (EFV-HAART) between baseline and 6 months;b)To describe the evolution of nutritional, body shape and metabolic response to continuous HAART therapy between 6-36 months Specific Aim II: In the untreated group, to describe the evolution of body composition and lipid changes with the natural progression of HIV infection (subjects must maintain CD4 between 300-500, if GD4 drops <200, therapy will be initiated and subjects will be withdrawn from the study). Study design: A 36 months prospective longitudinal study where study subjects recruited by HPTN study #052 with CD4 between 300 - 500 are randomized to either receive HAART treatment or remain untreated. All subjects in HPTN 052 will be asked to provide consent to enroll in this study in which they will be followed every 6 months for 3 years to observe body shape and metabolic changes Methods: Body shape and body composition changes will be assessed using anthropometry, BIA (every 6 months) and DEXA (yearly). Metabolic changes will be evaluated every 6 months by fasting lipids, insulin, glucose and 2hr glucose (yearly). Fasting lactate and C-reactive protein will also be measured every 6 months.